| As the rapid developing of solid state lighting, light-emitting diodes (LEDs) have shown great potential in application of road lighting. At present, high intensity discharge lamps (HID) such as high pressure sodium lamps (HPS) and ceramic discharge metal halide lamps (CDM) still play major roles as mature street lamps because of their high power and luminous flux emitted from small discharge arc tubes. However, rapid increasing traffic proposes the demand for higher quality of road lighting, which is characterized by high efficiency, good illuminance maintenance, long life-time as well as dimmable control. As HID lamps have limits in these aspects, LEDs become the right alternatives. Therefore, it is necessary to establish the evaluation system to compare the performance of HIDs and LEDs, so as to confirm the possibility of replacement.In-situ and laboratory measurements were conducted for the purpose of comparing the characteristic parameters and lighting performance of three kinds of street lamps:100 W LED street lamps,250 W HPS and 140 W CDM.In chapter one, the related background has been introduced, including the basic conceptions of road lighting, the main evaluation characters of lighting quality, the energy saving for road lighting, the misunderstandings in present applications, as well as the developing tendency of road lighting. Furthermore, the research method in this paper is described in detail and the innovation of the work is outlined.In chapter two, in-situ measurements for various street lamps is introduced, including the installation and measurement method, the instruments and devices, as well as the terminology. The measurement results in different stages are compared and evaluated to analyze their effects on road lighting quality. The illuminance maintenance of LED in 12000 h keeps at 86.4%, higher than that of HPS at 74.5%, which leads to low requirement for maintenance and consequently low cost. The luminance of LED is 13% higher than that of CDM,30% than that of HPS, which means the LED can provide better visual environment for both motor vehicle drivers and pedestrians.In chapter three, the test methods, evaluated characters and facilities are presented for laboratory measurements. The measured electric power of CDM is 10% higher than its rated power and that of HPS is 16% higher while that of LED is basically agreed, indicating that the actual energy consumption of HID is larger than their calculation values. As for color rendering, LED shows the best performance, improving the visual recognition. Beside, LED keeps the highest flux maintenance of 91.6% in 10000 h, compared to that of HPS less than 70%, ensuring the excellent energy saving performance in the whole life time.In chapter four, the glare becomes the focus, which is of great importance in road lighting. Three methods have been proposed to measure the degree of glare in road lighting, including the calculation method, the illuminance measuring method and the luminance measuring method. With these methods, the related parameters of various light sources are compared, which indicate a fact that the glare of LED is comparatively more severe than that of HID. Finally, the characters of the various light sources are calculated, simulated and analyzed through the measured luminous intensity distribution curves, and made comparison analyses against the measured results mentioned above, which shows that LED street lamps have a more uniform luminance and illuminance distribution on broader roads and features better parameters than HIDs.In chapter five, a conclusion of the whole study is delivered that LED street lamps have a clear advantage over HID street lamps in luminous efficacy, flux maintenance, power factor, life time and ratio of luminance to illuminance, etc. However, LEDs need to reduce the glare. In conclusion, LED street lamp is a promising road lighting system, which will play a significant role in improving the performance and reducing the energy consumption of the future road lighting. |
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